The G3100 is not mesh. It uses SON. With SON the router or extender will choose the 2.4 or 5 GHz band depending on the clients signal strength.
In a mesh system all the access points can communicate with each other.
Use can have multiple E3200s connected but they don’t communicate with each other. They all link back to the G3100. They can connect via coax, ethernet, or wifi.